A process is known from German Patent Application No. 38 15 615 for producing a high-blocking power diode, that results from doping a semiconductor material by diffusion. Boron and phosphorous are applied to the two main surfaces of a semiconductor body, and then in a first diffusion phase these two doping substances are brought to a particular diffusion depth-by warming the semiconductor body, to which they were applied, to a certain temperature. Also known is the use of doping foils for applying doping substances, which are placed on the semiconductor body. Suitable conditions for the first diffusion step are a diffusion temperature of, for example, 1200.degree. C. and a diffusion time of 30 hours in an oxidizing atmosphere. This diffusion process is also connected with a "getter" process, which provides for a sufficiently high charge-carrying lifetime. Next, thin metal layers are applied to the two exposed surfaces of the semiconductor body, where the kind of metal layer is determined by the field of use. For solder processes, for example, the layer sequence Al/Ni (aluminum/nickel) or Cr/Ni/Ag (chromium/nickel/silver) is suitable. Next, the semiconductor body is divided into chips by a sawing or other separation process. After the division, the individual chips are soldered between two contacts, that are composed advantageously of copper. After this soldering process, both surfaces of the chip ends are completely covered by solder and the contacts. The pn-junction that has been exposed on the sides and damaged by the sawing process is then etched with moist chemicals in a hot potash lye or in plasma, in order to eliminate the damages. Because of the covering of the chip-end surfaces by solder and the contacts, they are well protected against removal during the etching process. Then the prepared power diode can be covered with plastic, for example, so that it is protected passively and against environmental influences. Only when the power diodes are finally assembled and packaged can they be measured electrically and thus tested.
For the production of Zener (breakdown) diodes, the following process is known: A process used for the production of mesa diodes is used with epitaxy and photolithography steps. In addition, V-shaped grooves are etched, where the entire production takes place in clean-room conditions. Maintaining clean-room conditions leads to relatively high costs. For production of Schottky diodes, a photolithography step is likewise used and clean-room conditions are necessary. Also critical for series production is the contact between metal and silicon (Si), since this determines a well-defined state for the Si surface. Schottky diodes exhibit relatively high blocking-state currents and are not pulse-resistant.
Finally, it is also known that epitaxy layers and photolithography steps under clean-room conditions are necessary in the production of plane diodes.
In known processes for producing high-blocking diodes, the desired doping is first produced in a diffusion process, and then both wafer sides are metal-coated with, for example, Ni/Au (nickel/gold). Then both sides are coated with paint for protection of the metal coating against the following production steps. Next a grid is sawed, where the separation cuts are maintained by a specially V-shaped saw. Then an acid etching takes place within the grooves. Then, for passivation, the grooves are filled with polyimide paint by means of a doctor blade. Then the paint is stripped from the metal coating by a plasma stripper. Finally, separation into individual chips takes place by sawing.